This invention relates to a spot compression and magnification platform for aiding in compressing a small area of the breast of a woman undergoing a mammographic examination to displace glandular structure and enhance the quality of the image made by the mammography x-ray apparatus, and more particularly to a mounting base for adjustable attachment of the spot compression and magnification platform to the supporting platform of the mammographic unit.
The x-ray detection of the breast, known as mammography, can provide a sensitive and satisfactory means for examining women when screening for breast cancer, an abnormality which affects a significant percentage of the female population. The predictability of the results of the procedure, which is predicated upon an interpretation of the x-ray image produced, and thus the quality of the image, may in certain cases be indefinite and thus inconclusive. For example, many of the abnormal or suspicious soft tissue densities demonstrated are neither clearly benign nor malignant. Cancers, benign tumors, cysts, and asymmetrical areas of glandular tissue can all have similar appearances. Consequently, breast biopsies subsequent to mammographic examination using conventional compression of the breast disclose a relatively low positive yield for cancer, ranging from ten percent to thirty percent. Thus, it has been demonstrated that equivocal mammographic abnormalities require supplemental diagnostic procedures to avoid unnecessary breast biopsy.
One of the most useful additional procedures is a spot compression view which is performed with a small compression paddle to compress only a small area of the breast to increase the accuracy of the image and confidence of the interpretation, the small compression paddle being substituted for a larger conventional paddle. A spot compression view spreads apart glandular structures which can simulate a mass or hide the margins of a true mass. Such views can better define a mass seen on a routine view, and also distinguish abnormalities from those caused by superimposition of normal breast tissue. In the majority of cases a spot compression view shows the suspicious soft tissue density to be benign thereby eliminating unnecessary additional mammographic examination necessitating an additional dose of x-rays, and/or breast biopsy.
Conventional mammographic views utilize a large flat compression paddle which is pushed against the upper portion of the breast to compress the breast between the paddle and the imaging platform of the mammography apparatus. A smaller compression paddle is conventionally used to compress a small area over a potential abnormality in the breast when spot compression views are performed. All of the known compression paddles in the prior art are mechanically attached for use to the adjustable vertical column of the mammographic unit above the breast. When a suspicious area is located on an x-ray, the standard paddle is removed and replaced by the smaller spot compression paddle, which as aforesaid provides a localized compression and a higher quality view by moving normal glandular structure or tissue from dispositions which may be superimposed relative to the area of the breast which requires closer examination.
Many of the older mammographic units in operation do not have the capability of readily accepting spot compression paddles which, it is believed, are available only for the newer mammographic units. Because of the enormous capital expense required for acquiring such units, many hospitals and other diagnostic facilities having the older mammographic units have not made, and may be unable to make, such expenditures as are necessary. Additionally, even with those newer units that have spot compression paddles, because of the normal shape of a breast, i.e., the upper portion of the breast has a greater slope than the lower portion which is substantially horizontal, compression of the breast at the upper portion against the imaging platform may not provide as much clarity to the image as would appear to be the case were the breast to undergo additional spot compression from the lower portion. At least one manufacturer provides a rigid stool-like member for increasing the magnification of the image, but not for spot compression of the breast, the member being attachable to the image platform and having a large top portion on which the breast rests while the image is being made.
In U.S. Pat. No. 5,040,198, I have disclosed a number of freestanding spot compression and magnification devices positionable on the imaging platform of conventional mammographic units to obtain high degrees of focal breast compression and high quality images of a mass. These devices have magnification platforms incorporating a spot compression pedestal which improves contrast and spatial resolution, and can disperse superimposed normal glandular tissue which at times interfere with evaluation of an abnormal area of the breast. Devices constructed in accordance with the invention include an open bottom base having an upper platform including an opening about which an upstanding pedestal is disposed, the pedestal being open at the bottom and having a flat top surface upon which the breast of a patient may be disposed and compressed by a conventional mammographic paddle. An air gap is provided between the upper surface of the pedestal and the imaging platform of the mammographic unit and provides improved radiographic contrast resolution and magnification to the image.
These devices as aforesaid were free standing, being positionable upon the imaging platform of conventional mammographic units without mechanical attachment thereto. Although such a free standing relationship is satisfactory for the low magnification devices, high magnification spot compression devices require the magnification platform to be attached to the imaging platform of the mammography unit, i.e., the normal breast supporting platform must first be disassembled by completely removing a cassette holder containing a moving grid called a "Bucky" tunnel device. The grid, as known in the art, acts similar to a filter and is required when nonmagnified imaging is performed. The magnifying platform is then attached directly to the imaging platform and the film or the cassette holder is inserted between the imaging platform and the magnifying platform. Thus, conversion from a nonmagnified or lower magnified platform to a high magnified platform is awkward and time consuming.
In order to overcome this problem, the aforesaid copending patent application proposed a base having adjustable clamping handles having a set of locking tabs which adjustably enter within the opening or tunnel of the cassette holder to engage and grasp the cover and secure the device in position. However, there are two known sizes of "Bucky" tunnel devices, i.e., 18.times.24 cm. and 24.times.30 cm. The locking tab construction of the adjustable clamping handles disclosed in the aforesaid copending patent application is adapted for use with one such device, i.e., the smaller one, and if the larger "Bucky" device is on the mammographic machine it must be removed and replaced by the smaller device before the spot compression and magnification platform may be mounted on the machine. The present invention is adopted to overcome this inconvenience.